Scientists are struggling to determine exactly how, and to what extent, rising carbon dioxide levels will change the earth's climate.

In general, civilization releases about 6 billion tons of carbon (in the form of carbon dioxide) into the atmosphere every year. But only 3 billion tons stay there; the rest is absorbed into what are called carbon "sinks." Half of that dissolves into the ocean; the remainder ostensibly is taken up by vegetation.

Consequently, the performance of these sinks is an important variable in how much carbon dioxide is left in the air to trap heat and possibly raise global temperatures. Oceans absorb about one-third of all man-made carbon dioxide. They do so mainly in the cold regions because carbon dioxide dissolves easily into cold water, just like a soda in the refrigerator will stay bubbly much longer than a soda sitting in the sun. If the oceans didn't soak up carbon dioxide, the amount in the atmosphere would increase significantly faster.

Antarctica and the surrounding Southern Ocean provide scientists with a unique environment in which to study both past and present amounts of greenhouse gases in the atmosphere. The Southern Ocean is a delicate ecosystem where ocean current and microscopic sea organisms influence the release and burial of vast quantities of carbon dioxide. Analysis of biological activity and water motions suggest that rising temperatures in Antarctic waters favor the growth of microbial plants, which would help remove carbon dioxide from the atmosphere. On the other hand, a warming will liberate more carbon dioxide from tropical ocean waters, amplifying the greenhouse effect.

In examining past climate changes, scientists are collecting valuable ice core data and finding clues about natural climate patterns. Using evidence from hundreds of ice specimens, or "cores," taken far below the surface of Antarctica, investigators can analyze traces of air trapped within the ice cores for carbon dioxide content. From these samples, scientists can construct realistic models of climate change which may lead to effective solutions for the future.

Carbon Dioxide in the Atmosphere

All animals produce carbon dioxide when they exhale while plants take in carbon dioxide during photosynthesis.

Carbon Dioxide absorbs heat from the surface of the Earth, and prevents it from reflecting back into space, similar to the way a greenhouse works.

That is why carbon dioxide is called a "greenhouse gas."

Carbon dioxide and water vapor in the Earth's atmosphere together make the planet warm enough for life.

Of course, too much of the greenhouse gases can cause too much heating of the atmosphere: "global warming."

Burning fossil fuels produces a mixture of gases -and the principal one is carbon dioxide.